As a result of ever more stringent emission regulations and increased comfort requirements, the demands made of motor vehicles, in particular their injection systems, are rising continuously, specifically in the case of diesel engines. These stringent demands (efficiency, noise etc.) can be satisfied to a greater degree on the basis of better knowledge of the precise state of the system. It is then possible to react to changing conditions, for example the changing pressure or the changing temperature of the fuel, in such a way that disruptive influences are compensated. The knowledge of the fuel temperature in the high-pressure zone of the injection system is such a relevant variable, knowledge of which gives rise to better regulation of the pressure in the high-pressure zone of the injection system as well as to more precise metering of the injected quantity of fuel.
The aspects indicated above are relevant, in particular, for the fuel injection systems of diesel engines in which the fuel pressure and the fuel temperature in the rail have to be measured or monitored in order to achieve precise metering of the injected quantity of fuel. In this context, up to now either the temperature of the fuel in the high-pressure zone has been measured directly by means of a separate temperature sensor or the temperature has been calculated by means of modeling implemented with software.